Position sensor assembly, position-determining method, and linear actuator

Abstract

A position sensor includes first and second sensor components. The second sensor component has a reading unit that is configured to evaluate a capacitive signal in relation to the position of the second sensor component relative to the first sensor component. The position sensor is in addition configured to provide the result of the evaluation at an interface of the first sensor component. A method for ascertaining a position of a second sensor component of a position sensor relative to a first sensor component of the position sensor as well as a linear actuator, are provided.

The invention claimed is: 
     
       1. A linear actuator, comprising:
 a sheath tube; 
 a carriage disposed at least partly inside said sheath tube and mounted movably relative to said sheath tube; and 
 a position sensor disposed on said sheath tube and on said carriage, said position sensor including:
 a first sensor component disposed on said sheath tube and including an interface and a first electrode assembly extending within said sheath tube along an axial direction substantially along a travel path of said carriage, and 
 a second sensor component disposed on said carriage and including a reading unit, said reading unit having a second electrode assembly disposed opposite to said first electrode assembly for generating a capacitive signal indicative of a position of said carriage relative to said sheath tube, and said reading unit configured to evaluate the capacitive signal; and 
 
 said position sensor configured to provide a result of the evaluation at said interface. 
 
     
     
       2. The linear actuator according to  claim 1 , wherein the linear actuator, and said first sensor component includes a first electrode arrangement extending in an axial direction of said linear actuator. 
     
     
       3. The linear actuator according to  claim 1 , wherein said first electrode arrangement includes an electrode pattern varying in said axial direction and characterizing a position relative to said first electrode arrangement. 
     
     
       4. The linear actuator according to  claim 1 , wherein said first electrode arrangement is formed of a plurality of individual electrodes differing in at least one of their shape or their distance from one another. 
     
     
       5. The linear actuator according to  claim 1 , which further comprises:
 a circuit board having a side facing toward said first sensor component and a side facing away from said first sensor component; 
 said second electrode arrangement being disposed on said side of said circuit board facing toward said first sensor component; and 
 said reading device having evaluation electronics disposed on said side of said circuit board facing away from said first sensor component. 
 
     
     
       6. The linear actuator according to  claim 1 , which further comprises a transmission system for transmitting at least one of information regarding the position of said second sensor component relative to said first sensor component or energy between said reading unit and said interface. 
     
     
       7. The linear actuator according to  claim 6 , wherein said transmission system is an antenna system, and at least one of said first electrode arrangement or said second electrode arrangement form components of said antenna system. 
     
     
       8. The linear actuator according to  claim 7 , wherein said antenna system includes a first antenna arrangement connected to said interface and a second antenna arrangement lying opposite to said first antenna arrangement and connected to said reading unit. 
     
     
       9. The linear actuator according to  claim 8 , wherein said first electrode arrangement and said first antenna arrangement of said antenna system together form one component extending in an axial direction. 
     
     
       10. The linear actuator according to  claim 9 , wherein said component has a side facing away from said reading unit, and said first antenna arrangement is disposed on said side of said component facing away from said reading unit. 
     
     
       11. The linear actuator according to  claim 9 , wherein:
 said component has a side facing toward said reading unit; 
 said component has two sections on said side facing toward said reading unit; 
 said two sections extend parallel to one another in the axial direction; and 
 said first electrode arrangement and said first antenna arrangement are each disposed in a respective one of said two sections of said component. 
 
     
     
       12. The linear actuator according to  claim 1 , wherein said reading device is configured to generate position data based on the signal characterizing the position of said first sensor component relative to said second sensor component. 
     
     
       13. A method for determining a position of a sheath tube of a linear actuator relative to a carriage of the linear actuator disposed at least partly inside the sheath tube and mounted movably relative to the sheath tube, the method comprising the following steps:
 providing the linear actuator with a position sensor disposed on the sheath tube and on the carriage, 
 providing the position sensor with:
 a first sensor component disposed on the sheath tube and including an interface and a first electrode assembly extending within the sheath tube along an axial direction substantially along a travel path of the carriage, and 
 a second sensor component disposed on the carriage and including a reading unit, the reading unit including a second electrode assembly disposed opposite to the first electrode assembly, 
 
 generating a capacitive signal indicative of a position of the carriage relative to the sheath tube by using the reading unit; 
 evaluating the signal by using the reading unit; and 
 providing a result of the evaluation available at the interface.